1. Field of the Invention
The present invention relates to a battery pack which includes a rechargeable battery and is detachably connected to an electronic apparatus, and an electronic apparatus which receives power from such a battery pack.
2. Description of the Related Art
Most battery packs on the market do not include a function that enables authentication. The battery pack can be used if the outer shape and terminal positions of the battery pack conform to an electronic apparatus even if the battery pack is not a regular or an authenticated battery pack designed for the electronic apparatus. In general, a battery pack using a secondary battery (rechargeable battery), such as a lithium ion battery, includes a protection function in order to ensure the safety of users during charging and discharging of the battery. However, there is often a problem that a copy or unauthenticated battery pack has an insufficient protection function or does not even include a protection function. In this case, there is a possibility of causing a serious accident which may endanger the users.
In order to prevent the use of the unauthenticated battery pack, a battery pack has been developed which includes a circuit that can store identification information such as a serial number of the battery pack in a storage device such as an EEPROM. A simple authentication procedure is performed by a main apparatus to which the battery pack is connected. One example of the battery pack which can be used for such a simple authentication procedure is proposed in a Japanese Patent Application Publication No. 2006-164548.
However, although the battery pack is designed to enable the simple authentication procedure described above, an unauthenticated battery pack cannot be prevented from being used if the unauthenticated battery pack includes a similar storage device that stores a copy of the identification information. Thus, there is a problem that the simple authentication procedure would become ineffective.
This invention takes into consideration the problem described above, and thus one of objects of this invention is to provide a battery pack and an electronic apparatus with an authentication function that is difficult to copy.